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onsemi KSC3953DSTU
- Part No.:
- KSC3953DSTU
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-225AA, TO-126-3
- Datasheet:
-
KSC3953DSTU.pdf
- Description:
- TRANS NPN 120V 0.2A TO-126-3
- Quantity:
- Payment:
- Shipping:
Inventory:5,269
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Product details
Overview
KSC3953DSTU from ON Semiconductor (formerly Fairchild) is an NPN epitaxial silicon transistor designed for high-frequency video output stages in CRT displays, featuring VCEO = 120 V, fT = 400 MHz (typ.), and IC = 200 mA (DC), with TO-126 package and pinout E-C-B.
For engineers reviewing the KSC3953DSTU datasheet, pinout, applications, or equivalent options, key selection criteria include breakdown voltage margin, gain-bandwidth trade-off at 10–100 mA bias, saturation voltage under 30 mA/3 mA drive, and thermal derating above 25°C ambient or case temperature.
Technical Context
This transistor operates as a medium-power, high-fT NPN switch/amplifier optimized for analog video signal amplification where fast edge response and low reverse transfer capacitance are critical. Its 120 V VCEO rating supports flyback and deflection circuit operation in CRT horizontal output stages.
The device uses epitaxial base construction to achieve 400 MHz fT at VCE = 10 V and IC = 50 mA, while maintaining low Cre = 1.7 pF and Cob = 2.1 pF at VCB = 30 V - enabling stable high-frequency gain without parasitic oscillation in tuned load configurations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | 120 V - supports CRT horizontal deflection supply rails and transient voltage margins up to 120 V DC or peak. |
| fT | 400 MHz (typ.) - enables video bandwidth extension beyond 20 MHz with minimal phase shift in baseband amplifiers. |
| hFE1 | 40–80 @ IC = 10 mA - provides predictable DC bias stability for Class-A/B video driver stages. |
| VCE(sat) | 1.0 V @ IC = 30 mA, IB = 3 mA - limits conduction loss and self-heating during active switching in pulse-output applications. |
| Cre | 1.7 pF (typ.) - reduces Miller feedback to maintain open-loop gain and prevent instability in high-gain video amplifiers. |
| PC (TC=25°C) | 8 W - allows high-power dissipation when mounted on heatsink, supporting continuous 100–200 mA operation with thermal management. |
| TO-126 Package | Through-hole, 3-pin, epoxy-molded, with collector tab electrically connected to pin 2 - enables direct heatsinking and mechanical robustness in industrial display modules. |
Pinout & Package
TO-126 package: molded plastic case with metal collector tab (pin 2), standardized for through-hole mounting and heatsink attachment. Pin 1 = Emitter, Pin 2 = Collector (tab), Pin 3 = Base.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | Current sink terminal | Reference node for bias network; connects to ground or emitter degeneration resistor in common-emitter video amplifier. |
| 2 (Collector) | High-voltage output terminal | Electrically tied to metal tab - must be isolated from chassis unless grounded; carries full load current and flyback energy in CRT output stage. |
| 3 (Base) | Control input terminal | Receives drive current from preceding stage; requires ~3 mA for full saturation at 30 mA collector load per datasheet test condition. |
Key Features
| Feature | Design Value |
|---|---|
| High fT / low Cre combination | 400 MHz fT with only 1.7 pF Cre - preserves small-signal gain flatness across video band without neutralization. |
| 120 V VCEO rating | Supports operation in CRT horizontal output circuits with flyback voltages exceeding 100 V peak. |
| TO-126 thermal performance | 8 W power dissipation at TC = 25°C - enables reliable operation at elevated ambient temperatures with minimal heatsink area. |
| Low VCE(sat) at moderate drive | 1.0 V saturation voltage with 3 mA base drive - reduces power loss and improves efficiency in linear and switching video output stages. |
Applications
| CRT Horizontal Deflection Output | Video Signal Amplifier |
|---|---|
Use Scenario: Driving horizontal deflection yoke in analog CRT monitors with flyback recovery and high-voltage sweep waveform generation. IC Role / Device Role / Timing Role: High-voltage, medium-current NPN switch operating in Class-C or quasi-resonant mode with 15.734 kHz repetition rate. Use Value: 120 V VCEO withstands flyback spikes; 400 MHz fT ensures clean rise/fall edges on 2–5 µs pulses without ringing. | Use Scenario: Amplifying composite video or RGB baseband signals before CRT cathode modulation. IC Role / Device Role / Timing Role: Linear Class-A/B common-emitter amplifier with fixed emitter degeneration and capacitive coupling. Use Value: Low Cre (1.7 pF) minimizes feedback-induced distortion; hFE consistency (40–80) simplifies bias design across production lots. |
| Monitor Power Supply Switch | Industrial Analog Signal Buffer |
Use Scenario: Regulating auxiliary B+ supplies in CRT monitor SMPS using linear pass configuration. IC Role / Device Role / Timing Role: Medium-power series pass transistor controlled by error amplifier feedback loop. Use Value: 8 W PC (TC=25°C) supports >500 mW continuous dissipation with heatsink; VCE(sat) = 1.0 V lowers dropout and improves regulation efficiency. | Use Scenario: Isolating and buffering analog sensor outputs (e.g., thermistor, potentiometer) in industrial control panels. IC Role / Device Role / Timing Role: Unity-gain emitter follower providing low-impedance drive to ADC inputs or long cables. Use Value: High hFE (>40) ensures minimal base current loading; TO-126 mechanical stability resists vibration-induced solder joint fatigue. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar NPN high-voltage, high-fT transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MJD127G | VCEO = 100 V (lower), fT = 30 MHz (much lower), TO-220 package, higher PC = 15 W | Better for general-purpose linear regulation; unsuitable for CRT video bandwidth or flyback voltage margin | Select only if VCEO ≥ 120 V is not required and thermal budget exceeds 8 W. |
| 2SC4110 | VCEO = 120 V (same), fT = 250 MHz (lower), Cre = 2.5 pF (higher), TO-126 package | Acceptable for lower-bandwidth CRT deflection or audio output; reduced high-frequency fidelity vs. KSC3953DSTU | Use where cost is prioritized over 400 MHz fT and sub-2 pF Cre requirements. |
Compared with MJD127G and 2SC4110, the KSC3953DSTU uniquely delivers 120 V breakdown with 400 MHz fT and 1.7 pF Cre in TO-126 - making it irreplaceable for legacy CRT video output stages demanding simultaneous high voltage, speed, and stability.
Availability
KSC3953DSTU is available at Aetrix Electronics and suitable for CRT display repair, industrial analog signal conditioning, and legacy monitor power supply replacement requiring stable component supply and long-lifecycle support.
Supply support for KSC3953DSTU includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
ON Semiconductor (formerly Fairchild Semiconductor) is a global semiconductor supplier focused on energy-efficient power management, analog, and discrete devices for automotive, industrial, and consumer markets.
The KSC3953DSTU belongs to Fairchild's legacy high-frequency bipolar transistor product line, engineered specifically for analog video output and CRT deflection applications requiring high VCEO, high fT, and low capacitance.
FAQ
What is the maximum collector-emitter voltage rating for KSC3953DSTU?
The KSC3953DSTU has a guaranteed minimum VCEO rating of 120 V at TC = 25°C, verified per Absolute Maximum Ratings table. This rating applies under DC conditions and supports safe operation in CRT horizontal deflection circuits with flyback transients up to 120 V peak. Derating is required above 25°C case temperature per Figure 9 in the datasheet.
Does KSC3953DSTU have a built-in heatsink pad?
Yes, the KSC3953DSTU in TO-126 package features a metal collector tab (pin 2) that serves as both electrical connection and thermal interface. The tab is electrically connected to the collector and must be electrically isolated from other conductive surfaces unless intentionally grounded. Thermal resistance θJC is specified in the datasheet for heatsink mounting.
What is the typical current gain bandwidth product (fT) of KSC3953DSTU?
The KSC3953DSTU has a typical fT of 400 MHz measured at VCE = 10 V and IC = 50 mA, as confirmed in the Electrical Characteristics table and Figure 7 (Typical Characteristics). This value enables stable amplification of video-frequency signals up to ~20 MHz with adequate gain margin and phase stability.
Can KSC3953DSTU replace KSC3953 in existing designs?
Yes, KSC3953DSTU is a direct replacement for KSC3953 - both share identical electrical specifications, TO-126 package, pinout (E-C-B), and thermal ratings. The "DSTU" suffix denotes tape-and-reel packaging and RoHS-compliant lead finish; all functional and mechanical parameters match the original KSC3953.
What is the reverse transfer capacitance (Cre) of KSC3953DSTU?
The KSC3953DSTU exhibits a typical reverse transfer capacitance (Cre) of 1.7 pF at VCB = 30 V and f = 1 MHz, as specified in the Electrical Characteristics table. This low Cre value minimizes Miller effect in high-gain amplifier configurations and contributes to stable frequency response in CRT video output stages.
KSC3953DSTU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-225AA, TO-126-3
- Packaging:
- Tube
- Product Status:
- Obsolete
- Transistor Type:
- NPN
- Current - Collector (Ic) (Max):
- 200 mA
- Voltage - Collector Emitter Breakdown (Max):
- 120 V
- Vce Saturation (Max) @ Ib, Ic:
- 1V @ 3mA, 30mA
- Current - Collector Cutoff (Max):
- 100nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 60 @ 10mA, 10V
- Power - Max:
- 1.3 W
- Frequency - Transition:
- 400MHz
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-126-3
KSC3953DSTU FAQ
1.How can I place an order for KSC3953DSTU through Aetrix?
Please submit a Request for Quotation (RFQ) for KSC3953DSTU on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for KSC3953DSTU reliable?
The price and inventory of KSC3953DSTU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC3953DSTU is usually 5 days.
3.What payment methods are accepted for KSC3953DSTU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC3953DSTU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KSC3953DSTU?
KSC3953DSTU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KSC3953DSTU order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for KSC3953DSTU?
For technical support, including KSC3953DSTU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC3953DSTU requirements.
6.How does Aetrix verify that KSC3953DSTU is sourced from the original manufacturer or authorized distributors?
All KSC3953DSTU products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that KSC3953DSTU meets industry standards.
7.What is the process for return or replacement of KSC3953DSTU?
All KSC3953DSTU units undergo pre-shipment inspection (PSI). If there is an issue with KSC3953DSTU, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The KSC3953DSTU part is unused and in its original packaging.
Return procedure for KSC3953DSTU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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